added import_style parameter to generate import statements for browser that support es6

src/index.ts

@@ -5,7 +5,7 @@ import {CodeGeneratorRequest, CodeGeneratorResponse} from "google-protobuf/googl
 import {FileDescriptorProto} from "google-protobuf/google/protobuf/descriptor_pb";
 import {generateGrpcWebService} from "./service/grpcweb";
 import {generateGrpcNodeService} from "./service/grpcnode";
-import {ServiceParameter} from "./parameters";
+import {ServiceParameter, ImportStyleParameter} from "./parameters";
 
 /**
  * This is the ProtoC compiler plugin.
@@ -28,10 +28,11 @@ withAllStdIn((inputBuff: Buffer) => {
     const fileNameToDescriptor: {[key: string]: FileDescriptorProto} = {};
 
     const parameter = codeGenRequest.getParameter();
-    const {service, mode} = getParameterEnums(parameter || "");
+    const {service, mode, importStyle} = getParameterEnums(parameter || "");
 
     const generateGrpcWebServices = service === ServiceParameter.GrpcWeb;
     const generateGrpcNodeServices = service === ServiceParameter.GrpcNode;
+    const useImportStyleES6 = importStyle === ImportStyleParameter.ES6;
 
     codeGenRequest.getProtoFileList().forEach(protoFileDescriptor => {
       const fileDescriptorName = protoFileDescriptor.getName() || throwError("Missing file descriptor name");
@@ -47,7 +48,7 @@ withAllStdIn((inputBuff: Buffer) => {
       codeGenResponse.addFile(thisFile);
 
       if (generateGrpcWebServices) {
-        generateGrpcWebService(outputFileName, fileNameToDescriptor[fileName], exportMap)
+       generateGrpcWebService(outputFileName, fileNameToDescriptor[fileName], exportMap, useImportStyleES6)
           .forEach(file => codeGenResponse.addFile(file));
       } else if (generateGrpcNodeServices) {
         const file = generateGrpcNodeService(outputFileName, fileNameToDescriptor[fileName], exportMap, mode);

src/parameters.ts

@@ -8,3 +8,8 @@ export enum ModeParameter {
   None,
   GrpcJs
 }
+
+export enum ImportStyleParameter {
+    None,
+    ES6
+}

src/service/grpcweb.ts

@@ -5,10 +5,10 @@ import {FileDescriptorProto} from "google-protobuf/google/protobuf/descriptor_pb
 import {CodeGeneratorResponse} from "google-protobuf/google/protobuf/compiler/plugin_pb";
 import {createFile, RPCMethodDescriptor, RPCDescriptor, GrpcServiceDescriptor} from "./common";
 
-export function generateGrpcWebService(filename: string, descriptor: FileDescriptorProto, exportMap: ExportMap): CodeGeneratorResponse.File[] {
+export function generateGrpcWebService(filename: string, descriptor: FileDescriptorProto, exportMap: ExportMap, useImportStyleES6: boolean): CodeGeneratorResponse.File[] {
   return [
     createFile(generateTypeScriptDefinition(descriptor, exportMap), `${filename}_service.d.ts`),
-    createFile(generateJavaScript(descriptor, exportMap), `${filename}_service.js`),
+    createFile(generateJavaScript(descriptor, exportMap, useImportStyleES6), `${filename}_service.js`),
   ];
 }
 
@@ -100,7 +100,7 @@ function generateTypeScriptDefinition(fileDescriptor: FileDescriptorProto, expor
   return printer.getOutput();
 }
 
-function generateJavaScript(fileDescriptor: FileDescriptorProto, exportMap: ExportMap): string {
+function generateJavaScript(fileDescriptor: FileDescriptorProto, exportMap: ExportMap, useImportStyleES6: boolean): string {
   const serviceDescriptor = new GrpcServiceDescriptor(fileDescriptor, exportMap);
   const printer = new Printer(0);
 
@@ -116,9 +116,17 @@ function generateJavaScript(fileDescriptor: FileDescriptorProto, exportMap: Expo
   // Import Statements
   serviceDescriptor.imports
     .forEach(importDescriptor => {
-      printer.printLn(`var ${importDescriptor.namespace} = require("${importDescriptor.path}");`);
+      if (useImportStyleES6) {
+        printer.printLn(`import * as ${importDescriptor.namespace} from "${importDescriptor.path}";`);
+      } else {
+        printer.printLn(`var ${importDescriptor.namespace} = require("${importDescriptor.path}");`);
+      }
     });
-  printer.printLn(`var grpc = require("@improbable-eng/grpc-web").grpc;`);
+    if (useImportStyleES6) {
+      printer.printLn(`import {grpc} from "@improbable-eng/grpc-web";`);
+    } else {
+        printer.printLn(`var grpc = require("@improbable-eng/grpc-web").grpc;`);
+    }
   printer.printEmptyLn();
 
   // Services.
@@ -143,19 +151,23 @@ function generateJavaScript(fileDescriptor: FileDescriptorProto, exportMap: Expo
           printer.printLn(`};`);
           printer.printEmptyLn();
         });
-      printer.printLn(`exports.${service.name} = ${service.name};`);
+      if (useImportStyleES6) {
+        printer.printLn(`export {${service.name}};`);
+      } else {
+        printer.printLn(`exports.${service.name} = ${service.name};`);
+      }
       printer.printEmptyLn();
 
       // Add a client stub that talks with the @improbable-eng/grpc-web library
-      printServiceStub(printer, service);
+      printServiceStub(printer, service, useImportStyleES6);
 
       printer.printEmptyLn();
     });
 
   return printer.getOutput();
 }
 
-function printServiceStub(methodPrinter: Printer, service: RPCDescriptor) {
+function printServiceStub(methodPrinter: Printer, service: RPCDescriptor, useImportStyleES6: boolean) {
   const printer = new CodePrinter(0, methodPrinter);
 
   printer
@@ -177,7 +189,11 @@ function printServiceStub(methodPrinter: Printer, service: RPCDescriptor) {
     }
     printer.printEmptyLn();
   });
-  printer.printLn(`exports.${service.name}Client = ${service.name}Client;`);
+  if (useImportStyleES6) {
+    printer.printLn(`export {${service.name}Client};`);
+  } else {
+    printer.printLn(`exports.${service.name}Client = ${service.name}Client;`);
+  }
 }
 
 function printUnaryStubMethod(printer: CodePrinter, method: RPCMethodDescriptor) {

src/util.ts

@@ -1,7 +1,7 @@
 import {parse} from "querystring";
 import {FileDescriptorProto} from "google-protobuf/google/protobuf/descriptor_pb";
 import {ExportEnumEntry, ExportMessageEntry} from "./ExportMap";
-import {ServiceParameter, ModeParameter} from "./parameters";
+import {ServiceParameter, ModeParameter, ImportStyleParameter} from "./parameters";
 
 export function filePathToPseudoNamespace(filePath: string): string {
   return filePath.replace(".proto", "").replace(/\//g, "_").replace(/\./g, "_").replace(/\-/g, "_") + "_pb";
@@ -182,13 +182,27 @@ export function getModeParameter(mode?: string): ModeParameter {
   }
 }
 
+export function getImportStyleParameter(importStyle?: string): ImportStyleParameter {
+  switch (importStyle) {
+    case "es6":
+      return ImportStyleParameter.ES6;
+    case undefined:
+        return ImportStyleParameter.None;
+    default:
+      throw new Error(`Unrecognised import_style parameter: ${importStyle}`);
+  }
+}
+
+
 export function getParameterEnums(parameter: string): {
   service: ServiceParameter,
-  mode: ModeParameter
+  mode: ModeParameter,
+  importStyle: ImportStyleParameter,
 } {
-  const {service, mode} = parse(parameter, ",");
+  const {service, mode, import_style} = parse(parameter, ",");
   return {
     service: getServiceParameter(service),
-    mode: getModeParameter(mode)
+    mode: getModeParameter(mode),
+    importStyle: getImportStyleParameter(import_style)
   };
 }

test/helpers/fakeGrpcTransport.ts

@@ -23,7 +23,7 @@ function frameTrailers(trailers: grpc.Metadata): Uint8Array {
   trailers.forEach((key: string, values: string[]) => {
     asString += `${key}: ${values.join(", ")}\r\n`;
   });
-  const bytes = new Buffer(asString);
+  const bytes = Buffer.from(asString);
   const frame = new ArrayBuffer(bytes.byteLength + 5);
   const dataview = new DataView(frame, 0, 5);
   dataview.setUint32(1, bytes.length, false /* big endian */);